Young children's daily use of digital mobile media is becoming undeniably prevalent. It was reported that the daily amount of time children 8-years-old and under spent on mobile devices tripled between 2010 and 2012 (Common Sense Media, 2013). Children's seemingly intense interest in mobile devices and increased usage has prompted substantial public interest in mobile media's potential effects, benefits and consequences to children's development. Many organizations, program administrators, parents, and teachers are turning to research for answers. Unfortunately there is a paucity of direct evidence in this area, especially pertaining to young children from families who are managing poverty. Experimental studies examining the relationship between mobile media use and social-emotional outcomes such as executive function are non-existent. Utilizing an experimental research design, this 12-week randomized control trial (RCT) will investigate the relationships among Head Start (HS) preschool children's use of tablets, parent-child co-use of tablets and the children's executive function. Seventy-two (72) HS preschool children (ages 3 and up) and their parents will be recruited from 3 HS programs in the Midwest to participate in this study. The primary aim of the research is to ascertain whether HS children who independently and purposefully use educational apps on tablets demonstrate greater executive function than children who independently use apps of their choice, and whether children who co-use educational apps with their parents demonstrate greater executive function than children who use the same educational apps independently. Additional exploratory analyses will examine the relationships among children's executive function, the amount of time spent using a tablet, types of content being used, and parents' co-use of tablets with their children. This study also will introduce new, innovative, and more accurate methods of measuring the amount of time children and parents use mobile media, resulting in stronger validity of the study's analytical findings. This study will provide research-based information to HS programs and parents, to increase parents' understanding of how mobile media use at home may impact their child's development. HS program administrators will also be provided with needed empirical evidence as they consider how to use mobile media in their programs and practices, especially when working with parents. Also, the introduction of new methods of measuring time spent on mobile devices will improve the methodology practices used by researchers, strengthening the validity of future studies. And finally, the study's results will help to advance the nascent research found at the intersection of child development and mobile media.